1. Field of the Invention
The present invention relates generally to fluid dispensing devices. More particularly, the invention concerns an improved apparatus for infusing medicinal agents into an ambulatory patient at specific rates over extended periods of time which includes a novel actuating mechanism and a unique adjustable flow rate control means for precisely, adjustably controlling the rate of fluid flow from the reservoir of the device toward the patient.
2. Discussion of the Prior Art
Many medicinal agents require an intravenous route for administration of the medicament. The delivery device for delivering the medicament, while not an active pharmacologic agent, may enhance the activity of the drug by mediating its therapeutic effectiveness. Certain classes of new pharmacologic agents possess a very narrow range of therapeutic effectiveness, for instance, too small a dose results in no effect, while too great a dose results in toxic reactions.
In the past, prolonged infusion of fluids has generally been accomplished using gravity flow methods, which typically involve the use of intravenous administration sets and the familiar bottle suspended above the patient. Such methods are cumbersome, imprecise and require bed confinement of the patient. Periodic monitoring of the apparatus by the nurse or doctor is required to detect malfunctions of the infusion apparatus. Devices from which liquid is expelled from a relatively thick-walled bladder by internal stresses within the distended bladder are well known in the prior art. Such bladder, or “balloon”-type, devices are described in U.S. Pat. No. 3,469,578 issued to Bierman and in U.S. Pat. No. 4,318,400 issued to Perry.
One of the most versatile and unique fluid delivery apparatus developed in recent years is that developed by one of the present inventors and described in U.S. Pat. No. 5,205,820. The components of this novel fluid delivery apparatus generally includes: a base assembly, an elastomeric membrane serving as a stored energy means, fluid flow channels for filling and delivery, flow control means, a cover, and an ullage which comprises a part of the base assembly.
Another prior art patent issued to one of the present applicants, namely U.S. Pat. No. 5,743,879, discloses an injectable medicament dispenser for use in controllably dispensing fluid medicaments such as insulin, anti-infectives, analgesics, oncolylotics, cardiac drugs biopharmaceuticals, and the like from a pre-filled container at a uniform rate. The dispenser, which is quite dissimilar in construction and operation from that of the present invention, includes a stored energy source in the form of a compressively deformable, polymeric, elastomeric member that provides the force necessary to controllably discharge the medicament from a pre-filled container which is housed within the body of the device. After having been deformed, the polymeric, elastomeric member will return to its starting configuration in a highly predictable manner.
Another important prior art fluid delivery device is described in U.S. Pat. No. 6,063,059 also issued to one the present inventors. This device, while being of a completely different construction, embodies a compressible-expandable stored energy source somewhat similar to that used in the apparatus of the present invention.
As will be appreciated from the discussion which follows, the apparatus of the present invention is uniquely suited to provide precise, continuous fluid delivery management at a low cost in those cases where a variety of precise dosage schemes are of utmost importance. An important aspect of the apparatus of the present invention is the provision of a novel rotatable fluid flow rate control means that includes uniquely formed micro-capillary, multi-channel flow rate control channels which enable precise control of the rate of fluid flow of the medicament to the patient. More particularly, the apparatus of the present invention includes a novel adjustable fluid flow rate mechanism which enables the fluid contained within the reservoir of the device to be precisely dispensed at various selected rates.
The apparatus of the present invention can be used with minimal professional assistance in an alternate health care environment such as the home. By way of example, devices of the invention can be comfortably and conveniently removably affixed to the patient's body or clothing and can be used for the continuous infusion of analgesics and can be manufactured in both low flow and high flow configurations.
By way of summary, the apparatus of the present invention uniquely overcomes the drawbacks of the prior art by providing a novel, disposable dispenser of simple but highly reliable construction. A particularly important aspect of the apparatus of the present invention resides in the provision of a novel, self-contained energy source in the form of a compressible-expandable spring member that provides the force necessary to substantially, uniformly dispense various solutions from the device reservoir. Because of the simplicity of construction of the apparatus of the invention, and the straightforward nature of the energy source, the apparatus can be manufactured at low cost without in any way sacrificing accuracy and reliability.